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China Suppliers Factory Galvanized Countersunk Cross Tapping Screws – Quality Self-Tapping Solutions for Your Projects
| Thread specifications | ST2.2 | ST2.9 | ST3.5 | ST4.2 | ST4.8 | ST5.5 | ST6.3 | ST8 | ST9.5 | |||
| P | Pitch | 0.8 | 1.1 | 1.3 | 1.4 | 1.6 | 1.8 | 1.8 | 2.1 | 2.1 | ||
| a | Max | 1.6 | 2.2 | 2.6 | 2.8 | 3.2 | 3.6 | 3.6 | 4.2 | 4.2 | ||
| dk | Max | 3.8 | 5.5 | 7.3 | 8.4 | 9.3 | 10.3 | 11.3 | 15.8 | 18.3 | ||
| Min | 3.5 | 5.2 | 6.9 | 8 | 8.9 | 9.9 | 10.9 | 15.4 | 17.8 | |||
| k | Max | 1.1 | 1.7 | 2.35 | 2.6 | 2.8 | 3 | 3.15 | 4.65 | 5.25 | ||
| Slot Number | 0 | 1 | 2 | 2 | 2 | 3 | 3 | 4 | 4 | |||
| M1 | Cruciform | 1.9 | 3.2 | 4.4 | 4.6 | 5.2 | 6.6 | 6.8 | 8.9 | 10 | ||
| M2 | Zigzag slot | 2 | 3 | 4.1 | 4.4 | 4.9 | 6.3 | 6.6 | 8.8 | 9.8 | ||
| y | Reference value | Type C | 2 | 2.6 | 3.2 | 3.7 | 4.3 | 5 | 6 | 7.5 | 8 | |
| Type F | 1.6 | 2.1 | 2.5 | 2.8 | 3.2 | 3.6 | 3.6 | 4.2 | 4.2 | |||
| Type R | / | / | 2.7 | 3.2 | 3.6 | 4.3 | 5 | |||||
How to Choose a Suitable Self Tapping Screw
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Select by Material: Select different self tapping screws based on the material characteristics that need to be nailed in. For example, for hard materials, choose self tapping screws with high strength, appropriate length and diameter.
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According to Thread Selection: Self tapping screws usually have two types: coarse thread and fine thread, and different threads are usually suitable for different materials.
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Select According to the Shape of the Head: The pentagonal head self tapping screw is more sturdy than the ordinary round head self tapping screw, but the price is also relatively high.
Frequently Asked Questions (FAQ)
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Q1 What is the difference between coarse thread and fine thread self tapping screws?Coarse thread self tapping screws are generally used for softer materials such as wood and plastic, offering faster installation. Fine thread self tapping screws are better suited for harder materials like metal, providing a stronger and more secure hold.
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Q2 What does the "ST" designation mean in self tapping screw sizing (e.g., ST4.2)?"ST" stands for "Self Tapping." The number following ST (e.g., 4.2) refers to the nominal outer diameter of the screw thread in millimeters. A larger number indicates a thicker screw with a wider thread diameter.
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Q3 What is the advantage of galvanized self tapping screws?Galvanized self tapping screws have a zinc coating that provides excellent corrosion and rust resistance. This makes them ideal for outdoor applications or environments with high humidity, significantly extending the service life of the fastener.
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Q4 What are the differences between Type C, Type F, and Type R self tapping screws?Type C has a blunt point and is suitable for thicker materials. Type F features a sharp, tapered point for easier penetration into harder materials. Type R has a rounded or blunt tip designed for specific application requirements. Each type is optimized for different installation scenarios.
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Q5 How do I choose the correct length for a self tapping screw?As a general rule, the screw length should be at least 2–3 times the thickness of the material being fastened. The screw should penetrate deep enough into the base material to ensure a secure grip without protruding through the other side.
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Q6 What is the difference between a cruciform slot and a zigzag slot on a self tapping screw?A cruciform (Phillips/cross) slot is designed for use with a Phillips head screwdriver, offering good torque transmission and reducing the chance of slipping. A zigzag slot provides an alternative drive style that can offer better grip in certain applications, reducing cam-out during installation.